Ex vivo biologic effect

For additional evaluation of the effect of hydrophobization and the molecular weight of the polymers on the biological immuno-stimulating activity, we investigated the ex vivo cytokine (interIeukin-6 [IL-6], and tumor necrosis factor [TNFj-inducing activity from human peripheral whole blood cells of hydrophobized polymers by use of fractionated poly(M A-CDA) with narrow poly-dispersity. Since this assay uses the intact human cells, it shows more accurate results than in vitro assay using cultured cell line [25]. 

To obtain an increased intrinsic capacity to transgress biological membranes, a number of different modifications have been introduced to PNA. These modifications include conjugation of PNA to Hpophilic moieties [51, 97, 98], conjugation of PNA to certain so-caUed ceU-penetrating peptides [49, 55, 56, 66, 99-102] and conjugation to different moieties, which are supposed to be internahzed by specific cellular receptors [48, 103-105]. The work on cellular dehvery of PNA is, like the related work on ex vivo and in vivo effects of PNA, very difficult to summarize conclusively. First of all, the pronounced diversity of the reporter systems employed makes it impossible to directly compare the studies. Secondly, the widespread use of fluorescence studies in spite of the many inherent pitfalls of this technique makes it sometimes difficult to judge even qualitatively whether a presented result actually indicates cellular uptake. We have recently published a comprehensive review on cellular dehvery of PNA [82], with a more detailed assessment of the PNA dehvery hterature. 

Biological effects of SODs are widely studied in many in vitro, ex vivo, and in vivo experiments many of these studies have already been considered throughout this book. Examples of SOD application for the treatment of free radical pathologies are discussed in Chapter 31. Some studies related to the effects of SODs on free radical processes in cells and tissues are discussed below. 

In biological systems, therefore, the behavior of Li+ is predicted to be similar to that of Na+ and K+ in some cases, and to that of Mg2+ and Ca2+ in others [12]. Indeed, research has demonstrated numerous systems in which one or more of these cations is normally intrinsically involved, including ion transport pathways and enzyme activities, in which Li+ has mimicked the actions of these cations, sometimes producing inhibitory or stimulatory effects. For example, Li+ can replace Na+ in the ATP-dependent system which controls the transport of Na+ through the endoplasmic reticulum Li+ inhibits the activity of some Mg2+-dependent enzymes in vitro, such as pyruvate kinase and inositol monophosphate phosphatase Li+ affects the activity of some Ca2+-dependent enzymes— it increases the levels of activated Ca2+-ATPase in human erythrocyte membranes ex vivo and inhibits tryptophan hydroxylase. 

Figure 2. Polymer surfaces exposed to canine blood ex vivo for 60 minutes. Adherent objects are blood platelets. Top underivatized polyurethane bottom sulfonated polyurethane. Reprinted with permission of John Wiley Sons from Grasel, T. G., and Cooper, S. L Properties and Biological Interactions of Polyurethane Anionomers Effect of Sulfonate Incorporation, J. Biomed. Mater. Res. 23, 311 (1989) [16], Copyright 1989, John Wiley Sons.

A recent study has shown that the PERT assay can be used to monitor the effect of antiretroviral treatment of HIV-1 infected patients. In this study, HIV RNA by the Roche HIV Monitor assay (Roche Diagnostic Systems, Inc., Branchburg, NJ) became undetectable in 33 of 125 samples (26.4%) from 23 patients treated with an antiretroviral combination therapy. Particle-associated RT correlated well with the values of viral RNA, but remained above the detection limit of the PERT assay, even in samples that were negative by both PCR for viral RNA and a p24 antigen detection procedure shown to be as sensitive as PCR (14). Moreover, the susceptibility to RT inhibitors of virus populations taken from biological fluids ex vivo can be directly assessed in vitro, without a need to first amplify the virus in cell culture. Thus, the RT activity... 

The only way forward is to recognize that the modern, but still developing, techniques of cell biology and molecular biology, combined intelligently with the vast information storage and computational systems which are now available, should be applied directly to human material in vitro and ex vivo, and in some situations, subject to strict ethical controls, to human volunteers. Carefully planned and executed, this approach could take account of human polymorphism, past or concurrent disease, and the differential effects of age, occupation, lifestyle, and exposure to medicines and other chemicals. 

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